Gun perforator



Dec. 2, 1941. w. 0. MOUNCE 2,264,450

GUN PERFORATOR Filed April 15, 1939 3 Sheets-Sheet l 23 28 P30 32y K 7 l33 13$ A3; A

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M ATTORNEY.

w. D. MOUNCE 2,264,450

GUN PERFORATOR @e& 2, N41.

Filed April 15, 1939 3 Sheets-Sheet 3 Patented Dec. 2, 1941 GUN PERFORATOR Whitman D. Mounce, Houston, Tex., assignor to Standard Oil Development Company, a corporation of Delaware Application April 15, 1939, Serial No. 267,984

14 Claims.

The present invention is directed to borehole guns and firing circuits for borehole guns such as casing perforating guns and side wall coring guns.

In a gun of the character described, bullets are arranged radially in cavities along the surface of a gun barrel or body, these cavities being usually spaced from each other vertically and circumferentially. In the use of the gun, it is desirable to be able to fire the bulletsat any desired time, either at the same location or at different locations of the gun. In the majority of guns these bullets are usually fired by charges of powder which are ignited electrically, either by means of a heater wire in the powder or by an electric blasting cap in the powder.

In all existing arrangements, where the conductor connected to the source of power at the surface is connected directly to the firing elements, if a charge has been exploded, the conducting drilling fluid passes into the chamber, comes in contact with the exposed conductor and affects the electrical properties of the circuit. If the several igniting elements are of different resistance and are all connected in parallel, the drilling fluid short-circuits the remain ing charges and, since the conductance of ordinary drilling fluid is comparable to that of conductor cables ordinarily used for such purposes, it is extremely diificult, if not impossible to control the firing of the remaining charges.

This undesirable feature of firing circuits in which the resistances are arranged in parallel has been pointed out in U. S. Patent No. 2,141,- 827 in which it is proposed to arrange the various firing filaments in series, filaments of different resistances being employed in the various chambers.

In this case, as the charges are fired, provision is made for grounding the circuit both by the destruction of insulation of the electrical conductor to the explosive and by utilizing the conductance of the drilling mud to permit the firing of thelvremaining charges. However, if the mud comes in contact with the conductor to an unexploded ,charge, neither that nor any of the normally preceding charges can be fired. Furthermore, should any filament in the series be defective and broken for that reason, or should the filament fail to explode the charge in any given chamber, the remaining normally succeeding charges can not be fired.

The principal object of the present invention is the provision of a firing circuit for a gun of the character described in which the conductor firing current operating on a low voltage, thereby eliminating the high resistance of the cable between the source of power and the gun and making the conductance of the firing circuit high as compared to that of the drilling fluid with the consequent minimizing of difiiculties due to short circuits.

An additional object of the present invention is the provision of a gun of the character described made up into sections, each section containing a selected number of charges with switch means between the sections operable from the surface adapted to provide a positive control over the firing of the bullets in individual sections.

For a better understanding of the present invention, reference is made to the following detailed description of the accompanying drawings in which Figure 1 is a side view, partly in section, of a section of a gun perforator according to the present invention;

Figure 2 is a vertical section of the joint employed between gun sections;

Figure 3 is a cross section along the line A--A of Figure l;

Figure 4 is a schematic view of the firing circuit of the present invention; and

Figure 5 is a detail, partly in section, of a modified form of switch to be used between gun sections.

Referring to the drawings in detail, numeral l designates a section of a length of a gun body having screwed into its upper end ahead member 2 which receives cable 3 which is wound on a drum at the surface in a conventional manner. Cable 3 is an armored single conductor cable, the strands 4 of the armor of which are spread in a cavity 5 in head member 2, these strands supporting the weight of the gun. The strands are held in spread position by a washer and a plug 1.

The other end of heat. 2 is provided with a cavity 8 between which and cavity 5 is a passage for conductor 9 carried by cable 3, this con,-

'ductor terminating in a contact point ID in the upper end of cavity -8. Slidingly mounted in cavity 8 is a closed cylinder Ii in the upper end of which is a primary l2 of a transformer having one terminal connected to a contact button [3 which, in turn. is adapted to abut against con- I Preferably, the primary has an impedance which matches that of the cable, and the secondary has an impedance matching that of the firing circuit. Between the primary and the secondary of the transformer is a suitable core 18.

Into the bottom of cavity 8 is screwed a disk of insulating material carrying at its center a rivet 2!, one end of which is adapted to abut The abutting against one end of spring l8. faces of gun body i and head 2 are provided with complementary grooves to receive a packing ring The upper end of body I is provided with a central recess 22 in which is mounted a disk 24 of insulating material having at its'center a rivet 25 to the upper end of which is attached a U-shaped spring 26, the free end of which con To the lower tacts the lower end of rivet 2|. end of rivet 25 is attached an insulated conductor 21 which passes through a radial passage 28 to an external spiral groove 28 which extends the length of the section.

Spaced from each other longitudinally and circumferentially along'the length of section 1 are any desired number of diametrical bores 30, of

- which only one is shown,- havin'g interior threads adapted to receive'plugs 3|, which have anouter surface adapted to conform with the outer surface of section 1. Thethreaded portion of the a in the groove. This precaution is taken to prevent the leakage of borehole fluid into the powder.

soldered to the outer end of the bullet 31 is a conductor 48 which is connected to one end of a resistance coil 49 carried by a threaded stud 60 screwed into a suitable socket 6| in the gun body, preferably, as shown, in line with the spiral groove 29. The other end of the resistance coil is connected to conductor 21. The resistances 46 increase in value with successive bullets. The difference between these resistances need not be very great. but their value should vary logarithmically. For example, resistances of '0, .41, 1.0, 1.82, 2.54, 5.1. etc. ohms may be used in succession. At the lower end of the section, conductor 21 passes through a second radial passage 62 to the upper end of a-central bore 53 where it is attached to one end of a metal stud 64 passing through a disk 65 of insulating material screwed into the upper end of bore 63. Slidingiy mounted in here 53 is a cylinder 66 which carries at its upper end a leaf spring 6! the free end of which is adapted to contact one side of stud 54. The spring is carried by a stud 56 fixed in. an insulating plug 68 mounted in the upper end of cylinder 56, the inner end of said stud being connected to a conductor 60 inside of cylinder 56.

The conductor 66 is connected to a switching arrangement which comprises a pair of spring arms 6! and 62 carried bythe' plug 68 and depending-into the cylinder. The spring arms are made of bimetallic strips and are normally sprung inwardly toward each other sumciently to cause recess 30 extends substantially half way across the body of the gun section and is then converged lnwardly to form a concaved shoulder 62 which terminates in a cylindrical radial passage 33 which opens on the opposite side of the gun oarrel.

The plug 2| has a central cavity 90 on its inner face adapted to receive a capsule SI of conduc- ;ive material carrying powder, the outer end of vhich is closed by a disk 34 of insulating ma- ;erial through me center of which passes a rivet I5, to the inner end-of which is soldered a coil ilament 36 which is also grounded to the walls f the capsule. The outer end of the rivet is idapted to press against the inner end of a nullet 31 mounted in the cylindrical passage 33 .nd held in place by a circumferential flange 38, vhich extends into the body of the bullet and aterally thereof into a. recess 38 formed between h'e body of the gun body and a locking member 0 made of metal and shaped to fit the curved eat 32, said locking member having a central ore 4| adapted to receive the bullet. The bullet insulated from the gun body and the locking member by suitably placed disks 42 of insulating iaterial and an insulating sleeve 43. The inner 3.08 of the locking member is provided with an nnular groove 44 adapted to receive an annular allar 45 formed on the inner face of plug 3|. etween the locking member and the annular l1ar is packing material 46 and, for the purase of insuring the connection against leakage, llS packing material may be pressed into spaced rcumferential indentations 41 on the collar and is in its lower portion,

contact'between a button 63 carried by arm 62 and a button 64 carried by arm 6|, the latter buttonbeing connected to. a conductor 66 which in turn is connected to one end of a rivet 66 carried by an insulating disk 61 mounted in the lower end of thecylinder. .The spring arms are normally held apart by a spacer bar "pivoted at the lower end of arm 6! and having at its other end a slot 69 adapted to receive a pin 10 carried'by the lower end of arm 82. The slot 66 has such a configuration that, when the pin 10 the arms 6| and 62 are held away from each other by the bar 68, and when the arms 6| and 62 are spread apart the pin 10 moves into the upper portion of the slot which permits sufficient motion of the arms SI and 62 toward each other to cause buttons 63 and 64 to contact.

Conductor is connected to arm 62 and also to a heating coil H which is mounted on a post carried by plug 68 between arms 6! and 62 which is grounded to the wall of cylinder 56. When sufficient current is applied to the coil its heat causes the arms 6i and 62 to move away from each other. When this happens, the pin "I0 moves into the upper part of slot 69. Then, when the supply of current is shut off, the arms BI and 62 cool and bend toward each other, as previously indicated. After having cooled, the contacts are held together by virtue of pin 10 having moved into a vertical portion 12 of slot 69.

The lower end of section I is tapered and threaded to fit into a suitable socket in the next lower section. This socket carries an insulating disk the same as disk 24 heretofore described, so that electrical connection is made from one section to the next. It is to be noted that all sections are the same and are interchangeable.

Referring to Figure 4, it will be noted that the parts of the firing circuit shown in Figures 1 and 2 are referred to hereinbefore bear the same numerals. The conductor 9 is connected at the surface through a switch 13 to a pointer M which is'adapted to be slipped along the contacts of the secondary it of a transformer, the primary H of which is connected to an alternator 18. By adjusting pointer '14 the amount of voltage taken off the secondary can be regulated. This voltage is then impressed across the primary i2 and is suitably stepped down by the secondary l5 so as to supply a fairly large current with a low voltage to the firing circuit. In the firing diagram shown, conductors 19, B0, and 8i represent the gun body.

In Figure 5 is shown another form of switch which may be used in place of that shown in Figure 2. In this embodiment of the switch the arm 6| of the switch in Figure 2 is replaced by a rigid arm 82 of insulating material to which is attached the bar "68 and which carries also the button 64. A further difference betweenthe two embodiments is that in this embodiment the heating coil H is wrapped around arm 62. The principle'of operation is the same as that of the switch shown in Figure 2. is preferable, however, for the reason that in the embodiment shown in Figure 5, the arm 82 is a rigid part out of the gun body and moves with the body, whereby asudden movement of the body, as on recoil, might cause'the switch to close. Nevertheless, the switch shown in Figure 5 has been found satisfactory, it being understood that acci'dentalclosing will be an extremely rare occurrence. 1

From the above description, it will be apparent that by the use of the switch shown by either Fig. 2 or Fig. 5 the charges in the uppermost section of the gun may be fired, then by the operation of the switch the firing means in the adjacent section may be electrically connected to the power supply at the surface of the earth and the charges in this section fired. In other words, the firing means in a. lower section may be connected to the power supply only after the charges in the section above it have been iired.

It will be apparent that many changes in size, shape and arrangement of parts can be. made without departing from the scope of the present invention. For example, the gun body can be unitary rather than in sections. Again,

the groove carrying the conductor need not be helical. It is to be understood, therefore, that the specific construction described above is intended only as an illustration of one working embodiment of the present invention and is not intended to define the metes and bounds thereof.

I claim: v

i. In a gun for a borehole including a body, bullets arranged for projection from the sides of said body, and explosive charges arranged behind the bullets for the projection thereof, a firing circuit comprising aplurality of electrical devices arranged in said explosive charges for firing the same, said devices being arranged in parallel in said circuit, a source of alternating current for actuating said devices, and an inductive coupling between said source and said devices.

2. A gun. according to claim 1, in which the inductive coupling is a step-down transformer.

3. A gun for boreholes comprising a plurality of detachable sections, at least one projectile ineach of said sections, an electrical device for firing each projectile, a conductor electrically connected to a source of power andto said projectiles, and serially operable switching means The latter v operable from the surface arranged between said sections.

4. A borehole gun comprising a gun body adapted to be lowered into a borehole, a source of alternating current power adapted to be disposed at the surface, a single conductor cable connecting said source of power to said gun body,

, a transformer in said gun barrel having its primary connected to said conductor and to the ground, a conductor carried by said gun connected to the secondary of said transformer, bullets arranged in said gun for radial discharge, and electrical firing means for said bullet connected to said conductor.

5. A gun for bore holes comprising a plurality of detachable sections, a plurality of projectiles arranged in each of said sections for radial discharge, an electrical device for firing each projectile, a source of alternating current adapted to be disposed at the surface, electrical connections from said source of current to said projectiles, and switching means operable from the surface arranged between said sections.

6. In a bore hole gun a gun body comprising a plurality of detachable sections with at least one projectile in each section, a transformer in said gun body, electrical firing means for each of said projectiles, electrical connections from said firing means to a winding of said transformer and switching means operable from the surface arranged in said electrical connections between the sections of said body.

7. An apparatus as in claim 8 in which a source of alternating current adapted to be disposed at the surface is electrically connected to the other winding of said transformer.

8. A gun for bore holes comprising a pinrality of detachable sections, a transformer in one of said sections, at least one projectile in each of the remaining sections, electrical firing means for each of said projectiles, electrical connections from said firing means to a winding of said transformer, and switching means operable from the surface arranged in said electrical connections between the projectile containing sections.

9. A gun for a bore hole including a gun body comprising a plurality of detachable sections, a transformer in one of said sections, at least one projectile in each of the remainingsections, electrical firing means for each of said proiectiles,.a source of alternating current, electrical connections from saftl source of current to a winding of said transformer, and electrical connections from the other winding of the transformer to said firing means including switching means operable from the surface arranged between the projectile containing sections.

10. A bore hole gun comprising a gun body containing a transformer, a groove on the surface of said gun body, a conductor in said groove, a source of power connected through said transformer to said conductor, wells arranged on the surface of said body at spaced points along said tween s ductor, wells arranged on the surface of said bodYQ-Ptcjectiles arranged in said wells so that they co'me in direct cont-act with bore hole fluid as th'ef'gun is lowered in the bore hole, electriy'calzmeans' for firing said projectiles and electril onnections including said projectiles beaid conductor and said; electrical means.

liad-perforating device including a body adapte d to be lowered into a well bore, a plurality of explosive charges mounted in said body.

an electrical conductor extending from the surconductive mud in the bore after any of said shots have been fired, andmeans connected in the conductor for controlling the passage of current to the charge, said means being so arranged that each charge is fired by electrical current of a predetermined intensity, whereby said charges may be fired in a predetermined order.

13. An apparatus for electrically firing a plurality of explosive charges including an electrical circuit, a transformer in the circuit, and a series of electrical resistances forming part of said circuit and being associated with the explosive charges whereby the charges are successively fired by electrical currents of difiercut and progressively increasing intensities.

14. An apparatus for electrically firing a plurality of explosive charges including an electrical circuit, a transformer in the circuit, and a series of electrical resistances of varying capacities connected in the circuit, each resistance being associated with one of the charges so as to control the intensity'of the current required to fire said charge.

WHITMAN D. MOUNCE.

Disclaimer 2,264,450.-Whitma/n D. M ounce, Houston, Tex. GUN PERFORATOR. Patent dated Dec. 2, 19411. Disclaimer filed Aug. 9, 1951, by the assignee, Standard Oil Development Company. Hereby enters this disclaimer to claims 1, 2, 4, and 12 of said patent.

[Ofiicz'al Gazette September 11, 1.951.]

Disclaimer 2,264,450.Whitmam D. Mozmce, Houston, Tex. GUN PERFORATOR. Patent dated Dec. 2, 1941. Disclaimer filed Aug. 9, 1951, by the assignee, Standard Oil Development Company. Hereby enters this disclaimer to claims 1, 2, 4, and 12 of said patent.

[Oficz'al Gazette September 11, 1951.] 

